A
database of PIV measurements within a turbomachinery stage and
sample comparisons with unsteady RANS
O. Uzol, D. Brzozowski, Y.-C. Chow, J. Katz & C. Meneveau
Department of Mechanical Engineering
Johns Hopkins University, Baltimore, MD 21218
ABSTRACT: This paper describes an experimental database
obtained using two-dimensional Particle Image Velocimetry (PIV)
measurements within an axial turbomachinery stage, and presents
sample unsteady Reynolds Averaged Navier-Stokes (RANS) simulations
to illustrate its applicability for turbomachinery model validation.
The experiments are performed in a refractive-index-matched facility
that provides unobstructed view, and cover the entire second
stage of a two-stage axial pump. The data were obtained at ten
different rotor phases covering one rotor blade-passing period,
and at mid-span. Several features of the data at selected phases
have already been presented and discussed in prior publications.
Here we present the complete database together with sample CFD
results. Two-dimensional unsteady RANS simulations are performed
using the commercial flow solver FLUENT™, with two standard
turbulence models, i.e. Renormalization Group (RNG) k-epsilon
and Reynolds Stress Transport Model (RSM). The spatially non-uniform
inlet velocity and turbulence boundary conditions are provided
from the experimental data. Detailed side-by-side comparisons
of measured and computed velocity as well as turbulence fields
within the entire stage are presented using line distributions
within the rotor-stator gap and the stator wake regions, as well
as whole-field animations. The results show that, although there
is reasonable agreement, in general, between the experimental
results and the computational simulations, some critical flow
features are not correctly predicted. The turbulent kinetic energy
levels are generally too high in the simulations, with substantial
amount of unphysical turbulence generation near the blade leading
edges, especially in the case of RNG k-b.epsi model. Also, wake
diffusion is underestimated. The results highlight the usefulness
of comparisons that cover the entire unsteady flow in a passage,
as afforded by the present database and
side-by-side animations.
(2007)
J. of Turbulence 8, paper N10.
full
pdf paper
(© Taylor & Francis
, see http://www.tandf.co.uk/journals/titles/14685248.asp).
